As a safety precaution, explosive devices are generally packaged before being shipped. If one of the explosive devices explodes, the packaging is supposed to prevent the explosive force from being transmitted to surrounding structures and personnel, thereby preventing damage to both. In particular, the packaging is supposed to prevent the explosive force of a single detonation from initiating other explosive devices in the same shipment, which may start a chain reaction leading to mass detonation. As used by those skilled in the art, the term initiate means to fire, or explode, an explosive device.
As is known by those skilled in the art, the relative safety of packaged explosives is measured according to United Nations Certification numbers or classifications. Most detonators are in class 1.1B which means that they can mass detonate and, therefore, they must be shipped separately from other hazardous materials (except for materials having the same classification number). A 1.4B classification means that the explosives will not mass detonate and that they can be shipped with other hazardous materials. As it will be understood, products having a 1.1B classification are much more expensive to ship than products having a 1.4B classification, because they must be shipped on a truck separate from other explosives. An even more desirable classification is 1.4S, which means that the product can be shipped on commercial air-craft.
Several types of containers or packages for explosives are known that comprise layers of absorbent foam and/or metal barriers to contain an explosive force. None of these devices are practical for packaging detonators because they are expensive, whereas detonators are relatively low-cost items. Further, because of the complexity of many of the known packaging designs, they could not be produced in a size suitable for packaging a detonator, which is generally about 3 inches long and has a diameter of approximately 3/8 inches. Additionally, many of the explosives packages disclosed in the prior art are relatively heavy, which makes the assembled, packaged product difficult to handle and expensive to transport.
Generally, detonators are packaged by first layering a cardboard carton with 1/2" thick Homeosote. A 1" thick section of Homeosote is then provided and about 10-15 holes are bored in this Homeosote section. A detonator, having an explosive end, is then placed in each hole so that the explosive end is contained within the hole. A plurality of these boards containing detonators are placed in the carton with 1/2" thick Homeosote sheets placed between them. This type of packaging is relatively heavy and it does not adequately contain the explosive force of the detonator and, therefore, does not adequately prevent mass detonations. Additionally, it greatly reduces the available space within the carton. Therefore, each carton contains a relatively small number of detonators and transportation costs are increased.
Detonators are rated according to explosive force. A number 8 detonator has the lowest explosive force and a number 12 detonator has the highest explosive force. Using the packaging methods known in the prior art, it has been possible to achieve a 1.4B classification with number 8 detonators, but a 1.4B classification has not be achieved with more powerful detonators in a cost-effective manner and a 1.4S classification has never been achieved with detonators in a cost-effective manner.